Why do we use CASE Statement in SQL? Give example - SQL Interview Question


The CASE statement is similar to the IF ELSE statement in other programming languages.  We can use this to get or show particular values based on certain conditions.


Take a table student:

id name gender
1 Rahul M
2 Veronica F
3 Raj M
4 Preeti F
5 Ramesh M
6 Amit M

Now we will be going to implement a CASE statement to get gender Male for 'M', Female for 'F', and Other if nothing is defined.

SELECT id, name, CASE WHEN gender='M' THEN 'Male'
WHEN gender='F' THEN 'Female'
ELSE 'Other'
END AS gender
FROM student;

Output Table:
id name gender
1 Rahul Male
2 Veronica Female
3 Raj Male
4 Preeti Female
5 Ramesh Male
6 Amit Male

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